Cardiac Principles and Testing Quiz 1

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Cardiac Principles and Testing Quiz 1
2012-09-30 23:03:25
Cardiac Principles Testing Quiz

Quiz 1 for Cardiac Principles and Testing
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    • 1 LAD 1 LAD 1 LAD 1 LAD
    • 2 LAD 2 LAD 2 CX   2 LAD
    • 3 CX   3 RCA 3 LAD 3 RCA
    • 4 CX   4 CX    4 CX   4 LAD
    •             5 RCA 5 RCA 5 RCA
    •             6 CX    6 CX   6 LAD
  1. Sinus Tachycardia
    • Venntrricular rate > 100/min
    • Can be normal or pathological
    • Can occur in the presence of significant heart diease( heart blockage and tries to compensate)
    • CHF, severe pulmonary disease
    • Can be the only presenting sign of hyperthyroidism
    • Can result in diminished diastoilic perfusion
  2. Sinus Bradycardia
    • Ventricular rate < 60/min
    • Can be normal (ex: athlete) or pathological
    • Common rhythm disturbance in the early stages of acute myocardial infarction
    • In otherwise healthy individuals, can result from enhanced vagal tone (fainting)
  3. Sinus Arrhythmia
    • ECG appears normal in all apects except that the ventricular rhythm is irregular (regularly irregular)
    • Normal phenomenon - related to respiratory excursions (vagus tone from lung to heart)
    • Expected in young, healthy person
    • Caused by a decrease in vagal tone on teh SA node on inspiration - inspiration increase rate and expiration decrease rate
  4. Sinus Arrest, Asystole, and Escape Beats
    • Sinus arrest occurs when teh SA node stops firing; if no other site initiated pacing, this would progress to asystole -death
    • Generally, with sinus arrest, other myocardial cells outside of the SA node assume pacing function and "rescue" the heart called escape beats
  5. Nonsinus Pacemakers
    • Atrial cell pacemakers discharge at a rate of 60 to 75 beats/min
    • Juncitonal pacemakers located near the AV node discharage at a rate of 40 to 60 beats/min; most common route of escape beat
    • Ventricular pacemakers discharge at a rate of 30 to 45 beats/minute
  6. Sick Sinus Syndromes (SSS or tachy-brady syndrome)
    • Occurs when the cells of the SA node are not functioning reliably(maybe diminished blood flow to teh SA node)
    • SA node fires spooratically fast one moment and then slow the next (Not consistant generating beats)
    • Cannot depend on AV node for reliable pickup of pacing function - patient requires artifical pacemaker (SA still firing at the AV)
  7. Wandering Atrial Pacemaker
    • Ireegular ventricular rhythm due to constanly changing pacemaker focus in the atria but outside of the SA node
    • ECG - ireegularly spaced QRS complexes with normal, narrow configuartion: QRS complexes preceded by P waves that change in shape fro one beat to the next
    • Multifocal Atrial Tachycardia - changing atrial pacemaker with ventricular rate > 100/min
    • Seen in patient with COPD
  8. Ectopic Rhythms
    • Ectopic rhythms arise from elsewhere than the SA node - not escape beats, but sustained rhythms (continous)
    • At the ceullar level, ectopic rhythms are due to two physiologic mechanism:
    • Enhanced automaticity
    • Reentry
  9. Enhanced Automaticity
    • Normally, the SA node is fastest driver to heart; however, abnormal circumstances, any other of the pacemaker cells scattered throughout the heart can be accelerated
    • Any cell can be depolarized faster and faster until it overdrived the SA node an destablished its own transient of sustained ectopic rhythem - problem of impulse formation
    • Common cause of sustained automaticity is digitalis toxicity
  10. Reentry
    • Disorder of impulse transmission - results in the creation of a focus of abnormal electrical activity
    • Damage to an impulse pathway - results in interruption of conduction forward and transmission backward - causes an impulse to spin in a loop with waves of depolarization sent out in all directions
    • Reentry loop - overdrived the SA node and drived the heart (the loop exceeds the SA node)
  11. Ectopic Supraventricular Arrhythmias
    • Ectopic rhythms that originate in the atria or the AV node
    • Atrial premature beats (PAC) - single ectopic supraventricular beats (above the ventricle)
    • Junctional premature beats (PJC) occur in the vicinity of the AV node
    • Common - no pathology, no treatment
    • Danger - may initiate sustained arrhythmias
  12. Atrial Premature Beat
    Noted by contour of the P wave and the timing of the beat
  13. Junctional Premature Beat
    • Usually no visible P wave, but sometimes a retrograde P wave may be seen
    • Different from junctional escape beat because it occurs early, prematurely, interposing itself on the normal sinus rhythm; an escape beat is late, after a sinus pause
  14. Paroxysmal Supraventricular Tachycardia (PSVT)
    • Very common arrhythmia
    • Sudden onset; usually initiated by a premature supraventricular beat (atrial or juntional), its termination is just as abrupt as its onset (no idea why)
    • Can occur in normal hearts; may have no underlying cardiac diease; may be initiated by alcohol, coffee, or excitement
    • Absolutely normal rhythm, rate 150-250/min
    • Driven by reentrant circuit loop within the AV node in some patient
    • Retrograde P waves may sometimes be seen (at leads II and III)
    • Most commonly P waves are buried in teh QRS compexes and cannot be identified
    • QRS complexes are normal
  15. Atrial Flutter
    • Less common than PSVT
    • usually seen in patients with underlying cardiac pathology;  sometimes seen in mormal hearts
    • Ventricular rhythm regular; P waves occur at rate of 250 to 350/min
    • P wave - flutter waves - sawtooth pattern
    • AV node blocks some P waves - AV Block 2:1/(3:1/4:1) most common; cartoid massage may increase the AV block
  16. Atrial Fibrillation
    • Atria fibrillate above 350 beats/min
    • Distinct P waves are replaced by small fibrillation waves - the reentrant circuit is constantly changing; chaotic pattern
    • Ventricular rhythm - irregularly irregular
    • Ventricular rate 120-180/min
    • More common than atrial flutter - cardiac pathology often present; R/O hyperthyroidism, pulmonary embolism, and pericarditis
  17. Multifocal Atrial Tachycardia
    • MAT - irregular rhythm at rate of 100-200/min
    • Probably from random firing of several different atrial foci (if rate < 100/min, called wandering atrial pacemaker) only group of cell trying to generate beat
    • Common with severe lung diease (COPD)
    • P wave per each QRS complex; P waves vary in contour; PR intervals vary
  18. Paroxysmal Atrial Tachycardia
    • PAT - regular rhythm with rate of 100 to 200/min
    • Either from enhanced automaticity of an ectopic atrial focus or from a reentrant circuit within the atria
    • Commonly seen in otherwise normal hearts; most common cause is digitalis toxicity
    • Carotid massage has virtually no effect on PAT
  19. Premature Ventricular Contraction (VPC)
    • PVS - most common ventricular arrhythmia
    • QRS complex - wide and bizarre; ventricular depolarization does not follow the normal conduction pathways
    • Usually no P wave - rarely, a retrograde P wave
    • PVC - followed by a long pause before the next beat appears
    • Bigeminy (1:1) and trigeminy (2:1) normal beat to PVC
    • Isolated PVC common in normal hearts; rarely require treatment
    • PVC in presence of acute MI - ominous sign - can trigger ventricular tachycardia or ventricular fibrillation - life-threatening arrhythmias (oxygen deprive tissue will be sensitive - kick off PVC)
  20. When to Worry about PVC
    • Freguent PVC; runs of bigeminy or trigeminy
    • Runs of consecutive PVC, especially > 3 in a row
    • Multiform PVC (vary in site of origin and shape)
    • R on T phenomenon (ventricular tachycardia)
    • Any PVC in presence of acute myocardial infarction
  21. Ventricular Tachycardia
    • VT = 3 or more broad (>0.12 sec) QRS complexes that occur more than 100/min
    • May be tolerated well or be associated with decreased cardiac output and shock (cause ventricular fibrillation)
    • Atria beat independently in this rhythm because the AV node is rendered refractory to conduction by retrograde depolarization from the ventricles
    • Medical emergency, forecasts cardiac arrest; immediate Rx
  22. Ventricular Fibrillation
    • Ventricular fibrillation is a preterminal event; seen almost solely in dying hearts
    • Most frequently encountered arrhythmia in patients who experience sudden death
    • No true QRS compexes; no cardiac output
    • Required immediate cardiac defibrillation and cardiopulmonary sesuscitation
  23. AV Node Blocks
    • 1st Degree AV Block - Prolonged conduction at the AV node; PR interval > 0.2 seconds
    • 2nd Degree AV Block - Not every impulse is conducted through the AV node; two types
    • 3rd Degree AV Block - No impulse are conducted through the AV node; "complete heart block"; ventricular escape rhythm rate 30-45/min
  24. Wenckebach Block
    • 2nd Degree AV node block
    • Each successive atrial impulse encounters a longer and longer delay in teh AV node until one impulse (usually every 3rd or 4th ) fails to make it through
    • ECG - eventually a "dropped beat" is noted
    • Successive lengthening of PR interval until one P wave fails to conduct through the AV node and is not followed by a QRS complex
  25. Mobitz Type II Block
    • Due to a block below the AV node in teh His bundle
    • Diagnosis required the presence of a dropped beat without progressive lengthening of the PR interval (fixed PR but not drop out)
    • More serious and permanent damage to the conducting system (lower than the AV node) close to the Bundle of His; warning that a complete AV block (3rd degree block) may occur
    • Usually treated with artificial pacemaker
  26. Bundle Branch Block (BBB)
    • Complete block in either the left or right bundle branches of the common bundle of His
    • Depolarization is blocked ventricle is delayed because conduction occurs more slowly via gap junctions between muscle cells. Delay in depolarization results in QRS complexes that are abnormally wide, more than 0.12 seconds (patches of cell in the bundle causing delay)
    • Diagnosis - look at width an dconfiguration of the QRS complexes (will have p wave)
  27. Right Bundle Branch Block
    rabbit ear
  28. Left Bundle Branch Block
    • R wave is not sharp
    • wide, bizarre QRS complex and p wave.
  29. Pacemaker
    • Demand pacemaker - fires only when the patient's own intrinsic rate falls below a threshold level (sense P wave)
    • Pacemaker spike - spike before ensuing QRS compex
  30. Who need Pacemaker
    • 3rd degree AV block
    • Lesser degree of AV block or bradycardia (sick sinus syndrone) if symptomatic
    • AMI with AV block and bundle branch block
    • Recurrent tachycardias that can be overdriven by a pacemaker
  31. ECG Diagnosis of Acute Myocardial Infarction
    • T wave peaking followed by T wave inversion
    • ST segment elevation
    • Appears of new Q waves
  32. Mycocardial Infarction
    • Acute - infarct, injury, ischemia
    • Subacute - infarct, ischemia
    • Chronic - infarct only
  33. Hyperkalemia
    Tall, peaked T waves, need blood work to confirm
  34. Hypokalemia
    Flattening of T waves and developemnt of U wave